We have retrospectively analyzed the incidence of diabetic nephropathy in 21 diabetic patients who underwent renal biopsy between 1985 and 1995 for microscopic hematuria and/or proteinuria >2.5 g/day without retinopathy. Diabetic nephropathy was observed in 13 of 21 patients (62%). 50% of our patients with diabetic nephropathy had hematuria, the incidence being higher in type I as compared with type II diabetic patients (30 vs. 20%). Diabetic nephropathy without retinopathy but with hematuria was noted in 5 of 13 patients, and diabetic nephropathy without retinopathy and hematuria was also noted in 5 of 13 patients. We suggest from our retrospective analysis that renal-retinal diabetic syndrome really exists.